The present invention relates to a vibration damper the damper comprising a body part, by means of which the damper can be fastened to the object to be dampened, an oscillating piece movably arranged in the space of the body part, the oscillating piece being connected to the body part by at least one spring.
The invention also relates to a method for producing a vibration damper.
The invention further relates to a vibration dampening arrangement of an engine.
The vibration of a piston engine is known as such, and in order to reduce it, there are a number of various solutions, such as balancing solutions. In engines there can be noted vibration forms of which both the engine and the auxiliaries attached in connection therewith, such as a compressor or compressors, are part of. In this case it is a matter of a global vibration form, i.e. the engine and its subconstruction/s together form a vibration system. The engine can also include local vibration of a certain auxiliary, whereby the dynamic properties of the auxiliary are determining as far as the vibration is concerned.
Control of local vibrations is usually easier than control of global vibrations of the whole construction. In local vibration the rigidity, fastening, mass etc. can be modified more easily. In the control of the global vibration of the engine, however, the need for modification can be directed at the engine itself, whereby it may be required to increase the rigidity of the cylinder block etc. This is, naturally, impossible, in case there is a desire to use standard engine components. The viewpoint of costs must also be considered when looking for new solutions.
In all types of vibration, the mass and gas forces of the engine act as the stimuli of the engine. A special difficulty in vibration dampening of engines is that the vibration properties of engines of different sizes (number of cylinders, cylinder diameter etc.) differ from each other. Further, the engine running speed also has an effect on the vibration.
In order to dampen the vibrations, U.S. Pat. No. 5,816,373, for example, discloses a solution, in which an oscillating piece is arranged between springs in a space containing compressible gas. Because the operation of the damper depends on, among others, the mass of the oscillating piece and its dimensions (throttling), the properties of the gas and the properties of the springs, such a solution will always have to be dimensioned and produced individually for dampening a vibration of a certain frequency.
The aim of the present invention is to produce a vibration damper minimizing the problems associated with prior art. Another aim of the invention is to produce a vibration damper the dampening properties of which can easily be changed even after the manufacture.